With the increasement of the population of elder peoples, the population suffering Alzheimer's disease increases rapidly. Alzheimer's disease is also referred to as Alzheimer type dementia or senile dementia of the Alzheimer type. Currently, although the incidence of this disease worldwide is unknown, according to the latest report from Alzheimer's Association of the United States, about 5.4 million of people suffering Alzheimer's disease until 2011 in the United States, and the population suffering this disease in the United States will increase to about 13.5 million until 2050 in the United States. Therefore, there is an urgent need for developing novel drugs for the treatment of this disease with higher efficiency and lower adverse effects.
Alzheimer's disease is the most common senile dementia, and has become the 6th cause of death of American, and the 5 th cause of death of American aged 65 or older. Although this disease has been researched widely and deeply by scientists, the exact reason causing this disease is still unknown. Alzheimer's disease is a progressive disease, and it kills nerve cells continuously and breaks the neural connections in brain, resulting in the break of the tissues in brain, and in turn resulting in the loss of memory, consciousness, and judgment of patients, as well as emotional disorder and behavior disorder in the patients.
Alzheimer's disease is a kind of irreversible disease, and there is no drug can prevent this disease and there is also no drug can cure this disease or prolong the progress of this disease. Nowadays, the drugs for treating this disease can only relieve or improve the symptom of this disease. There are 5 drugs that have been approved by FDA of United States, wherein 4 of them are inhibitors of acetylcholinesterase. Acetylcholine is a kind of neurotransmitter, and is a chemical substance released by nerves. If the system generating acetylcholine, i.e. the cholinergic system, in the brain is broken, memory disorder associated with Alzheimer's disease will be caused. Whereas, the function of acetylcholinesterase is to catalyze the hydrolysis of acetylcholine, i.e., to degrade acetylcholine. Since Alzheimer's disease is accompanied with the decay of acetylcholine activity, the inhibition of acetylcholinesterase is thus one of the approaches for treating this disease. As mentioned above, 4 of the 5 drugs that have been used for the treatment of Alzheimer's disease in clinical are inhibitors of acetylcholinesterase. There inhibitors of acetylcholinesterase include donepezil, tacrine, rivastigmine and galantamine, wherein donepezil is the first-line drug for the treatment of Alzheimer's disease (Sugimoto et al. U.S. Pat. Nos. 4,895,841 and 5,100,901; Pathi et al. WO 2007077443; Parthasaradhi et al. WO 2005003092; Dubey et al. WO 2005076749; Gutman et al. WO 200009483; Sugimoto et al. J. Med. Chem. 1995, 38, 4821). However, donepezil and the other 4 drugs can only improve the condition of patients, and such improvement is only transient, i.e. can only last 6-12 months, and also, the response rates of the patients to these drugs are only about 50% (Alzheimer's Association, 2011 Alzheimer′ Disease Facts and Figures, Alzheimer's & Dementia, 2011, 7(2), 208). The present invention provides novel acetylcholinesterase inhibitors, which are novel benzodioxole derivatives and are drugs for the treatment of Alzheimer′ disease, having higher efficiency and lower adverse effects in comparison to donepezil.